Start 'Em & Sit 'Em is the ultimate look at the weekly NFL matchups and how they'll affect your fantasy football team. Sleeper alert features an under-the-radar player who could produce good numbers. Owners beware features a regular fantasy starter who could fail to meet expectations based on the strength of his opponent. Obvious fantasy starters like Aaron Rodgers and Arian Foster will not be featured in this column. For your final lineup decisions, check our lineup rankings.
Start of the week
Ryan Mathews at New Orleans Saints: I know, I had Mathews in this spot last week. And yes, he didn't even start. But I'm not convinced the Chargers are going with Jackie Battle as their new runner. In fact, I think Mathews will have his best game of the season against the Saints. No team has allowed more fantasy points to running backs, and Mathews will be motivated to produce.
Frank Gore vs. Buffalo Bills: Gore has had some tremendous matchups in recent weeks, and the streak will continue against the Bills. Their defense is dreadful against the run, which was evident last week when Steven Ridley and Brandon Bolden ripped them for a combined 242 yards and three touchdowns on the ground. That makes Gore a very solid fantasy option across the board.
Reggie Bush at Cincinnati Bengals: Bush seemed to escape last week's loss to the Arizona Cardinals with no setbacks, so his knee should no longer be a problem. That's good news, as is this week's matchup in the Queen City against the Bengals. Their defense has surrendered five total touchdowns and an average of 22.20 fantasy points per game to opposing running backs this season.
Alfred Morris vs. Atlanta Falcons: Morris has been one of the true surprises of the 2012 fantasy football season, rushing for 376 yards and four touchdowns in his first four games. I'd keep him active as a No. 2 runner or flex starter against the Falcons, who rank a mediocre 18th in run defense and have allowed an average of close to 20 fantasy points per game to opposing runners.
Sleeper alert - Cedric Benson at Indianapolis Colts: Benson has become a bigger part of the Packers offense in recent weeks, averaging 18.3 touches and 11.5 fantasy points in his last three games. Those are attractive totals from a back who is a flex starter in most leagues. The Colts have allowed the eighth-most fantasy points to backs, so Benson should post another nice stat line.
Sit of the week
Fred Jackson at San Francisco 49ers: Rule No. 1 in the world of fantasy football running backs: If a player faces the Niners, chances are his numbers are not going to be attractive. That's the scenario this week for Jackson, who goes up against a defense that has surrendered the fewest fantasy points (7.78 PPG) to opposing runners. That's bad news for Jackson and C.J. Spiller as well.
DeAngelo Williams vs. Seattle Seahawks: If we have learned anything in the last few weeks, it's that the Seahawks defense is good. Darn good. In fact, this unit has allowed just two touchdowns and the third-fewest fantasy points to opposing backs in 2012. That makes Williams, who has been inconsistent at best after four games, a major risk. The same holds true for Jonathan Stewart.
BenJarvus Green-Ellis vs. Miami Dolphins: The Dolphins might have just one win in their first four games, but their run defense hasn't been to blame. This unit ranks fifth in the league in stopping the run, in fact, and has surrendered an average of just 14.23 fantasy points per game to running backs. That makes the inconsistent Green-Ellis a risk as more than a simple flex option.
Rashard Mendenhall vs. Philadelphia Eagles: Mendenhall is back for the Steelers, and he should now be rostered in all fantasy leagues. That doesn't mean that he should jump right back into your starting lineup, however. This weekend's matchup against the Eagles is a tough one, as the birds from Philadelphia have surrendered the seventh-fewest fantasy points to running backs.
Owners beware - Chris Johnson at Minnesota Vikings: I don't want to rain on your parade, as Johnson is coming off his best statistical game of the 2012 season. And while you will likely end up starting him with the bye weeks in full swing, just keep this in mind. After four weeks, only the 49ers have given up fewer fantasy points to opposing running backs than the Vikings.
Michael Fabiano is an award-winning fantasy football analyst on NFL.com. Have a burning question on anything fantasy related? Tweet it to **@Michael_Fabiano** or send a question via **Facebook**!